Today, gas heating is still the cheapest. Therefore, if there is a main gas pipeline and technical capabilities nearby, it makes sense to install a double-circuit gas boiler. Why dual circuit? Because one device will provide both heat and hot water.
The wall-mounted double-circuit gas boiler has the dimensions of a small cabinet
When choosing a double-circuit boiler, be sure to pay attention to several parameters:
- installation method: floor-wall;
- power;
- type of combustion chamber (open, closed);
- type of heat exchanger and material from which it is made;
- set of service functions.
There are many other points, but these are the main ones. Without them, it is impossible to choose a double-circuit gas boiler; we will talk about them further. First of all, let’s get acquainted with the structure of this equipment and the principle of its operation. Then all the stages of choosing a gas boiler for a house, apartment or cottage will be clear.
Floor-standing gas boiler and storage boiler nearby
Structure and main differences
A gas boiler consists of three main modules - a burner, a heat exchanger, and automatic control. The burner is located in the combustion chamber, above it there is a heat exchanger in which the coolant is heated. The entire process is controlled by automation. It ensures safety and changes the operating modes of the equipment.
Boiler with a closed combustion chamber (turbocharged)
Types of heat exchangers
A double-circuit boiler is distinguished by the fact that it can heat both water for heating and water supply. This must be done separately, because special heat exchangers are needed. There are two types:
- Double heat exchanger. It consists of two separate modules - primary and plate. In the primary, the coolant from the heating system is heated, in the secondary - plate - water for domestic needs. The primary heat exchanger is a tube with fins, the secondary is a set of plates. They are located in different parts of the boiler - primary at the top, plate at the bottom, but they are connected to each other so they can be read as a single part.
- Bithermal heat exchanger. It consists of two metal tubes of different diameters inserted into one another. In the inner tube, water is heated for hot water supply, in the outer tube - for the heating system.
The structure of a double-circuit gas boiler
A system with a dual heat exchanger is more reliable. Since heating is a closed system and the coolant circulates in a circle, little scale is formed. When heating water for hot water supply, the situation is the opposite - running water heats up, which means there is a lot of scale. This part of the heat exchanger periodically requires repair or replacement. If in a dual heat exchanger it is possible to replace only the part that heats water for domestic needs, then in a bithermal heat exchanger there is no separation; you have to change the entire device, and this is much more expensive. There is one more point: a double-circuit gas boiler with a double heat exchanger works normally for heating, but with a bithermic the situation is different - it does not work at all.
Heat exchanger material
The choice of a double-circuit gas boiler can also be influenced by the material from which the heat exchanger is made. It could be:
- Stainless steel. A good option in terms of durability, but it has rather low heat transfer, which reduces the efficiency of the boiler. However, the price of such a heat exchanger is high.
- Cink Steel. This is the cheapest type of heat exchanger, but also the most short-lived.
- Copper. An excellent option for heat transfer (boilers have high efficiency) and durability, but the price is high. But this scares few people - it outweighs the opportunity to pay less for gas during operation. It is for this reason that most good double-circuit gas boilers are equipped with a copper heat exchanger.
This is what the primary heat exchanger looks like in gas wall-mounted boilers
Choosing a double-circuit gas boiler based on this parameter is not so difficult. Copper seems to be the best option. Not without its drawbacks - high chemical activity and low melting point - but they have long learned to compensate for them. The boiler automation ensures that there is no overheating. Chemical activity is neutralized by using chemically neutral materials in the heating system - using polymer pipes - polypropylene or cross-linked polyethylene.
Types of burners for gas boilers
In wall-mounted double-circuit gas boilers, atmospheric gas burners are installed. According to the method of controlling the flame, they are:
- Single stage. The burner either burns or it doesn’t. There are no intermediate provisions. To maintain the required heating mode, the burner either lights up or goes out. Not the best working algorithm.
- Two-stage. There are two operating modes - at 100% power and at 50-60%. The automation itself regulates the required power. Such burners are more economical and allow you to maintain the temperature more accurately. By reducing the number of on/off switches.
Double-circuit gas boiler with modulating burner is the most economical
If we talk about the optimal choice, then these are modulating burners. They not only allow you to maintain the heating temperature accurately, but also heat the water exactly to the specified parameters. If you want to choose an economical double-circuit gas boiler, it must have a modulating burner.
Automation
Automation is a must in gas boilers - it ensures safety and switches operating modes. There are three main parameters that are constantly monitored:
- presence of draft in the chimney;
- gas pressure;
- flame control.
These are key points that simply need to be monitored. If at least one of these parameters is not normal, the boiler does not turn on. In addition, there is an extensive list of additional functions:
- Maintaining a stable temperature. There are two types of automation: one controls the temperature of the coolant, the second controls the air in the room. More comfortable conditions are created by controlling the air - the weather changes, but regardless of this, the set mode is maintained in the room.
This is the remote control from which all parameters are set
These are the functions that are common, but there are also specific ones: the ability to connect (and control) solar panels, underfloor heating systems. There is weather-compensating automatic control. In this case, there are remote sensors that are installed on the street. Based on their data, the operation of the boiler is adjusted.
Ferroli Diva gas boiler control panel
All these functions are embedded in the microprocessor, which controls everything. Of all the automation systems, the average user only encounters a remote thermostat, which can be installed in any room and based on the readings of which the temperature can be adjusted (another additional feature). Basically, all interaction with the boiler and its automation is limited to a small panel. All necessary information is displayed on the screen. There are also buttons with which you change modes and set the temperature.
How does a single-circuit mounted gas boiler work?
Gas single-circuit wall-mounted heating boilers have a simple design consisting of:
Burner device.
Automation that regulates work.
- Security systems.
- The heated coolant enters the heating system. After heat transfer, the liquid returns to the boiler through the return pipeline and re-enters the heat exchanger.
The operating principle and design of a wall-mounted single-circuit gas heating boiler varies depending on the internal design. Changes lead to a decrease or increase in thermal efficiency and efficiency.
The consumer is offered boiler equipment with a closed and open combustion chamber, using the principle of condensation heating, as well as turbocharged boilers.
The coolant is heated as follows:
- The gas burner turns on.
Above the burner device there is a heat exchanger with liquid circulating in it.
Single-circuit mounted gas boilers have high efficiency and heat transfer, and are distinguished by their productivity.
What types of wall-mounted heating boilers with one circuit are there?
The range of boiler equipment with a single-circuit heat exchanger is presented quite widely. Selecting the optimal option is difficult, especially if you take into account the design and thermal differences of the proposed equipment.
To narrow the search, all boilers are classified into several groups, depending on the characteristics of the devices:
Atmospheric boiler is the classic version of the equipment. A wall-mounted single-circuit gas boiler with an open combustion chamber, also called atmospheric or convection. During operation, air is taken from the room to maintain combustion. The removal of combustion products occurs through natural draft in the chimney. As a rule, boilers with an atmospheric burner are equipped with mechanical controls. The operation is regulated by thermostats, as well as an installed thermocouple. Ignition is performed manually using a piezoelectric element.
A boiler with a closed combustion chamber is equipment with forced air intake and removal of combustion products. Fans or turbines are used to circulate air and exhaust gases. Boilers with a closed combustion chamber, in turn, are divided into two classes:
- Turbocharged engines have a closed combustion chamber. Equipped with a modulating burner. They got their name because of the design features. The device uses one or two turbines that pump air into the burner and remove combustion products. A feature of the boilers is the modulation of the power of the burner device together with a change in the rotation speed of the fans. The efficiency of a single-circuit turbo boiler is in the range of 95-98%.
Another criterion for classifying boilers is the type of burner used during operation:
- Single-stage burner device - installed in single-circuit non-volatile wall-mounted gas boilers. The burner maintains the heating temperature of the coolant according to the principle of turning on/off the combustion mode. Be sure to install an igniter that works constantly.
Two-stage burners - have two operating modes, 30% and 100% power. Improved burners use smooth switching of output, which reduces gas consumption. The burners operate in constant mode, without shutting down. When the coolant is heated to the required temperature, the power of the burner device is automatically reduced to 30%. Starting is carried out by electric ignition. The change in power is controlled by electronic automation, which makes boilers with two-stage burners energy-dependent.
The main purpose of single-circuit boilers is heating residential premises. Modern models, with minor design modifications, are capable of simultaneously heating water for domestic hot water.
How to perform DHW with a single-circuit boiler
You can get hot water from a single-circuit boiler by connecting an indirect heating boiler to the heater.
Some models are already equipped with built-in storage capacity. The connection of a mounted single-circuit boiler with an external boiler proceeds as follows:
- The container is installed within 2-3 meters from the boiler.
The boiler closes the supply and return pipelines and forms a small circle of the heating system.
A three-way valve is installed on the supply pipeline.
A single-circuit gas wall-mounted boiler with a built-in boiler does not have the disadvantage that distinguishes models connected to an external storage device. Heating of the heating system is carried out simultaneously with heating of water for hot water supply.
Almost all modern boilers offered by consumers have the ability to connect an indirect heating boiler, which significantly expands the functionality. The piping requires significant material costs for the purchase of a storage tank and the necessary fittings.
Which single-circuit boiler heat exchanger is better?
Single-circuit mounted boilers are equipped with a heat exchanger made of stainless, enameled steel or copper. The walls of the circuit, due to weight restrictions, are made thin, which leads to relatively rapid burnout of the metal. The service life of modern heat generators reaches 20 years.
Various additives are added to the steel from which the heat exchanger is made, affecting the technical and operational characteristics of the boiler, and the possible type of coolant for single-circuit boilers is determined.
For this reason, not every heat exchanger is suitable for antifreeze. Before purchasing a suitable model of boiler equipment, pay attention to the operating instructions provided by the manufacturer.
If the manual says that the heat exchanger is not resistant to chemical components, filling the heating system with antifreeze is strictly prohibited. Failure to comply with the recommendations leads to a significant reduction in the life of the boiler and denial of warranty service.
Installation method
Depending on the installation method, gas boilers can be floor-mounted or wall-mounted. Wall-mounted - compact installations, the size of a small kitchen cabinet. They do not require equipment in a separate room and can be installed in the kitchen or other suitable room. The maximum power of a wall-mounted gas boiler is 30-35 kW. This is usually enough to heat rooms with a total area of 250-350 square meters. m.
Floor-standing gas boilers are more powerful and, accordingly, have larger sizes and weight. There are models that can be installed in a living space, while others require a dedicated room - a boiler room. Installation requirements are prescribed by each manufacturer separately, but usually the distance from the top of the boiler to the ceiling, the volume of the room and the presence of ventilation are specified.
Wall-mounted gas boilers are larger in size and weight, but this is due to their higher power
Regardless of the type, a certified project is required to install gas boilers. The diagram must include a gas meter, so if it is not there, you will need to purchase one. Connection work must be carried out by a company that has a license for this type of activity. Only in this case will the boiler be put into operation.
Selecting a double-circuit gas boiler based on installation method is simple. If there is enough power, they usually take a wall-mounted version, if not, a floor-mounted one.
Well-known companies and manufacturers
Single-circuit wall-mounted gas boilers are popular devices that are in high demand. For this reason, such designs are produced by all well-known manufacturers of heating devices.
Recognized leaders in this field of technology are German companies:
Italian companies practically do not lag behind them either in quality or in price:
Gas boilers from Czech and Slovak companies are distinguished by high quality and affordable prices:
In addition to them, Korean boilers from Navien or Kiturami, as well as Russian Lemax, Aton, Siberia, ZhMZ, are widely known. All these models are of high quality, capable of working in different conditions and performing their tasks in residential, public or industrial premises.
Combustion chamber type
The gas burner is located in the combustion chamber. There are two types - open (atmospheric) and closed (with a turbine, forced). A double-circuit gas boiler with an open combustion chamber can only be installed in rooms with good ventilation. During operation, the oxygen necessary for combustion is taken from the room, and combustion products are discharged into the chimney with good draft. Therefore, a good air flow and a properly functioning exhaust ventilation duct are necessary.
Gas boilers come with open and closed combustion chambers
Gas boilers with a closed combustion chamber are distinguished by the fact that at the chamber outlet there is a coaxial chimney (pipe within a pipe) equipped with a fan. The chimney is taken out into the street, or into the wall near the boiler. Through one pipe, air is taken in from the street, through the second, combustion products are removed, their movement is ensured by a fan-turbine.
Which combustion chamber is better? A boiler with a closed combustion chamber operates more stably - air enters directly into the combustion zone. But there is also a disadvantage to this: with a side wind, the air flow can be so strong that it blows out the burner and the boiler turns off. The second disadvantage of this solution is freezing and the formation of ice in winter. Well, the third drawback is that such a boiler only works when there is electricity - without a turbine it turns off. Well, there is another small minus - the turbine is not silent. It’s almost inaudible, but it’s “almost.” Apparently for these reasons, if possible (a working ventilation duct), boilers with an open combustion chamber are installed. After all, ensuring a constant flow of air is much easier.
Principle of operation
The operating principle of single-circuit boilers is quite simple, and a higher education in engineering or physics is not required to understand all the design flaws. During installation, the device is connected to the chimney; in most cases, natural draft is sufficient, but you can install additional hoods and special fans if you want to avoid blowing out the flame. This is especially worth doing if you decide to cut the price and purchase more than one of the automated devices that have built-in protection against almost everything and turn off the gas supply if the flame goes out.
Boilers come with open and closed combustion chambers. The first type is most often used, but it also requires compliance with certain conditions during installation. And, first of all, you should worry about fire safety by covering the walls with special heat-resistant paint or additional protection. It is also necessary to comply with sanitary and hygienic standards of cleanliness.
Important. Oxygen is required for the flame to fan and burn freely, and combustion products, if installed incorrectly, can easily pollute the boiler room. Accordingly, it is better to install autonomous heating in a separate room or annex.
Gases harmful to the human body can accumulate even with free airflow into the boiler, so it is necessary to take care of additional exhaust hood. All the conditions described will maximally protect the autonomous heating system, eliminate interruptions and blowing out the flame, thereby protecting you and your family from the risks of explosion and spontaneous combustion of the room. But still, before making any design sketches, contact and consult with a specialist. This will save you time and give you confidence that your technical specifications and drawing will be approved by the gas service.
Boiler power
One of the key points in choosing a heating boiler is determining the required power. If we approach this with full responsibility, it is necessary to consider the heat loss of each room, if we are talking about an apartment or a building as a whole, if the boiler is selected for heating a private house. The calculations take into account the materials of the walls, their thickness, the area of windows and doors, the degree of their insulation, the presence/absence of an unheated room below/above, the type of roof and roofing material. Geographical location and a whole bunch of other factors are taken into account.
Such a calculation can be ordered from a specialized organization (at least in GorGaz or a design bureau), if desired, you can do it yourself, or you can take the path of least resistance - calculate based on average standards.
Where does the heat leave the house?
Based on the results of all calculations, a standard was derived: heating 10 square meters of area requires 1 kW of heating power. This standard is suitable for rooms with ceilings of 2.5 m, with walls with an average degree of thermal insulation. If your room falls into this category, divide the total area that needs to be heated by 10. You get the required boiler power. Then you can make adjustments - increase or decrease the resulting figure depending on real conditions. It is necessary to increase the power of the heating boiler in the following cases:
- The walls are made of material with high thermal conductivity and are not insulated. Brick and concrete fall into this category for sure, the rest - depending on the circumstances. If you are choosing a boiler for an apartment, you need to add power if the apartment is corner. For “internal” ones, heat loss through them is not so terrible.
- The windows have a large area and do not provide airtightness (old wooden frames).
- If the ceilings in the room are higher than 2.7 m.
- If in a private house the attic is not heated and poorly insulated.
- If the apartment is on the first or last floor.
The design power is reduced if the walls, roof, and floor are well insulated and energy-saving double-glazed windows are installed on the windows. The resulting figure will be the required boiler power. When searching for a suitable model, make sure that the maximum power of the unit is not less than your figure.
The best single-circuit gas boilers with an open combustion chamber
In the first selection we will look at boilers with an open burner. Let us remind you that such equipment uses air from the room, and sends combustion products into the chimney naturally. This is generally a simpler and more affordable scheme.
Lemax Gazovik AOGV-6, 6 kW, single-circuit
Rating: 4.6
For heating a small room up to 50 square meters. meters, boilers of minimum power are suitable. One of the most inexpensive options is the domestically produced Lemax boiler from the budget Gazovik series with a capacity of 6 kW. There are also more powerful modifications in the series; we are considering this one as an example. This option is one of the most popular.
The simplest possible scheme is used here, in which there is only minimal automation without any frills, which determines the affordable price. For the same reason, the boiler is completely autonomous - it does not need a connection to the electrical network. Installation - floor.
The heat exchanger here is made of steel with walls 2 mm thick. Manufactured in accordance with Russian GOST, and also meets European standards and even American ASTM A 1011.
The efficiency of this model is not a record, but still quite high for the super-budget class - 87%. It is achieved due to the expanded heat exchange area and turbulators, which partially delay the removal of gases.
The most important functional modules use imported high-quality components - a POLIDORO micro-torch burner and Italian-made safety automatics.
The boiler control is mechanical, manual; when adjusting, you can navigate using the built-in thermometer. There is no pump, meaning the coolant circulates naturally. There is a gas control with automatic shutdown of gas supply in case of spontaneous extinguishing of the burner.
Advantages
- gas control;
- relatively good efficiency, as for a simple boiler;
- imported burner and safety automation;
- complete energy independence;
- thermometer;
- easily removable casing;
- the most affordable price.
Flaws
- minimal functionality.
Lemax Premium-10, single-circuit
Rating: 4.7
Now a more powerful and functional model of the same domestic brand Lemax Premium series. This is also a boiler with a floor installation, which even outwardly is almost identical to the previous one, but they differ not only in power.
In addition to the power of 10 kW, which is already enough to heat a room of 100 square meters. meters, there is also a slightly higher efficiency - 90%. The principle is the same - the boiler uses the same steel burner and imported automation. But to the mandatory gas control function, automatic overheating control has also been added. This does not mean overheating of the device itself, but of the water in the heating system. If the coolant temperature begins to exceed the set maximum, the boiler automatically turns off.
This model is also non-volatile. It is understood that a connection to an outlet is not required for operation, but the control, accordingly, is also only mechanical and water circulation should be natural. Let us remember that the disadvantage of such systems is that, due to the absence of a pump, it will not be possible to maintain uniform pressure. The minimum pressure in the system must be 13 mbar for the unit to produce the stated 10 kW heating power and 90 percent efficiency.
Users in reviews on trading platforms praise this model mainly for its simplicity, reliability and fault tolerance. Rare complaints about the burner going out for no reason are often due to installation irregularities, and not to fundamental shortcomings of the device.
A special feature of the model is that at a set temperature of up to 50 degrees, condensation can form inside. The manufacturer considers this phenomenon as the norm, but users are often wary and note it as a drawback.
Advantages
- decent efficiency;
- overheat protection;
- imported automation and burner;
- energy independence;
- gas control;
- thermometer;
- convenient removable casing.
Flaws
- Under certain conditions, condensation forms.
Buderus Logamax U054-24, 24 kW, single-circuit
Rating: 4.7
The next boiler in this collection has gone far in terms of characteristics from the previous version. It is almost twice as expensive, but in its class it is considered inexpensive. Another plus is that the Buderus trademark is nothing more than a division of the legendary BOSH.
This model is much more powerful - 24 kW is enough to heat an area of up to 240 square meters. meters, and that's just the nominal value. And according to user reviews, the device can easily cope with large rooms.
And its main advantage is not even power, because this figure of 24 kW is one of the most common. The most important thing here is the presence of a built-in expansion tank with a capacity of 8 liters. This tank gives the boiler a huge advantage, as it allows you to effectively compensate for the thermal expansion of the heat exchanger and, accordingly, the excess water that arises due to this.
The second big plus is the copper heat exchanger. This is the most expensive option, but it is also the optimal one - sufficient corrosion resistance, durability, light weight, high thermal conductivity, compactness, light weight - only 32 kg.
The boiler is equipped with a whole set of automation. These are protective equipment - gas control; protection against overheating, freezing and pump blocking. And also effective automatic adjustment of flame intensity, plus auto-ignition based on sensor readings. There is a thermometer and a pressure gauge.
The disadvantage is the lack of a circulation pump. The presence of a pump blocking protection function is a tribute to the mass production of various modifications, and often misleads buyers.
The boiler can also operate on liquefied gas. The efficiency is one of the highest in this class - 91.35%. You can connect external control.
Advantages
- BOSH division;
- expansion tank;
- copper heat exchanger;
- automatic protective kit;
- auto ignition;
- flexible automatic adjustment;
- built-in pump;
- high efficiency;
- compactness.
Flaws
- no circulation pump.
BAXI SLIM 1.300 iN, 29.7 kW, single-circuit
Rating: 4.8
Now let’s look at a much more expensive, but at the same time much more functional boiler from the BAXI brand. The manufacturer is an Italian company with a half-century history, which is now part of the German-British holding BDR Thermea. Conventionally, this model can be classified as high middle class, closer to premium.
This is a fairly powerful 29.7 kW boiler with floor installation. In the BAXI model range it is considered compact - the SLIM series with dimensions of 350x850x680 mm. But the weight is as much as 126 kg, due to additional equipment and heavy coolant.
An important role here is played by the built-in pump, which regulates the stability of the coolant pressure. A big plus is the ultra-reliable cast iron coolant made of five sections. The level of useful thermal power in combination with the characteristics of the burner themselves provide decent energy efficiency and an efficiency of 90%.
Moreover, the device is also equipped with an electronic control system that provides automatic flame modulation. All this makes it possible to heat large rooms up to 220 square meters. meters with noticeable savings in resources.
The presence of automation and a pump already makes this model energy-dependent - it requires a connection to a 220V power supply to operate.
This model is suitable for heating private houses, cottages, commercial and industrial premises. It can work as part of cascade heating systems, as well as in “tandem” with an external boiler for heating water in the water supply system.
Another notable feature is support for operation in two temperature ranges. So, the range from 30 to 45 degrees allows you to use this boiler for the operation of a “warm floor” system.
Additional functions and capabilities: protection systems against overheating, freezing, gas attenuation, pump blocking; automatic self-diagnosis; connection of external control; auto ignition; possibility of working on liquefied gas.
Advantages
- reputable brand;
- ultra-reliable heat exchanger made of cast iron;
- flame modulation;
- multifunctional protective automation;
- electronic control;
- connection of external control;
- suitable for “warm floor”;
- relatively compact.
Flaws
- installation only in a separate room.
Buderus Logano G234 WS-44, 44 kW, single-circuit
Rating: 4.9
The selection will be completed by the most expensive boiler in the category. This is also a model of the Buderus brand, but a fundamentally different device than the wall-mounted compact Logamax U054-24. It costs about 200 thousand rubles at the beginning of 2022.
This price may be upsetting, but this is only at first glance. The boiler is almost twice as powerful as the previous one - 44 kW, but it is the power that directly determines the cost of the boiler, even within the same series. Here the emphasis is on increased reliability, durability and reliability for operation with an intensity comparable to industrial use. Its resource is enough to heat rooms up to 440 square meters. meters.
With such power, the device also demonstrates a top efficiency indicator - 93%. And this despite the fact that it is convection, not condensation. In this case, this is more of a plus, since with potentially maximum intensity of use this provides fewer reasons for breakdown.
The boiler is large and heavy, for floor installation it weighs 221 kg. Here a significant share of the weight falls on the cast iron heat exchanger. The manufacturer also made a choice towards maximum durability - such heat exchangers last for 50 years.
The device operates in automatic mode, has auto-ignition, and supports flame modulation. You can connect external control. Like many other boilers in this class, it can operate on liquefied gas.
For such a price, however, many users do not have enough of a circulation pump and an expansion tank. And electronic automation would greatly benefit from auto diagnostics, which is also not available here. The manufacturer can be understood, since the emphasis was placed on reliability during long-term continuous operation. But still, the price is somewhat obligatory.
Advantages
- manufacturer;
- premium class;
- power;
- reliability, reliability and durability;
- high efficiency;
- protective automation;
- flame modulation;
- connection of external control;
- operation on liquefied gas is possible.
Flaws
- no pump and expansion tank;
- price.
Double-circuit gas boilers: manufacturers
Having decided on the technical characteristics, all that remains is to find a suitable model and choose a manufacturer. This is not at all easy - there are many companies on the market, prices vary considerably. As usual, there are three segments - expensive, mid-priced and cheap.
Expensive ones are products from European manufacturers:
- Italian gas boilers - Ferroli, Beretta, Ariston, Baxi.
- The German ones are not inferior to them in quality: Viessmann (Weissmann), Wolf (Wolf), Vaillant (Vialant).
- Korean Navien (Navien) are worthy competition to the leaders.
This equipment works reliably and without failures, but only under certain conditions. The first is a stable power supply, without significant deviations in frequency and voltage. Our networks lack stability, so a voltage stabilizer is needed, preferably an electronic one. The second condition for normal operation is a certain gas pressure in the line. Most German and Italian gas boilers operate if the gas pressure is 2 atm or more. The exception is the Ariston and Navien boilers.
Manufacturers of double-circuit gas boilers number in the dozens
Russian-made wall-mounted double-circuit gas boilers - Danko, Protherm - have proven themselves well on the market. They have approximately the same functionality as the “Europeans”, but react less sharply to deviations in the power supply and operate at low gas pressure. What is not pleasing is the Russian “service”.
There are also Bosch boilers. The company itself is German, but there are factories in Russia, so it’s not easy to determine the geographical location of these boilers - some are produced in Russia, some at other factories in other countries. Bosh campaign specialists have developed a new boiler model adapted to our conditions - Gaz 6000 W.
Gas is one of the most popular types of fuel, which has one of the most optimal efficiency and price ratios. These days, more than half of the installed heating equipment runs on gas. The market offers a wide range of products, which is difficult even for a professional to choose from.
The selected model of gas boiler must be as reliable as possible and fully satisfy the needs of the buyer. Before purchasing, you need to answer several questions regarding the type of equipment you are purchasing, power, functionality, desired level of comfort, etc.
The best single-circuit gas boilers with a closed combustion chamber
The second selection is devoted to another common type of gas boilers - with a closed combustion chamber. Such models require air intake from outside the room, but do not need a chimney - exhaust is provided by forced ventilation, with rare exceptions.
Lemax Patriot-10, 10 kW, single-circuit
Rating: 4.7
First, let's look at the most inexpensive closed version of the already familiar domestic brand Lemax Patriot series. It costs less than 40 thousand rubles at the beginning of 2022.
This is a model of relatively low power - 10 kW, which is enough to heat a small house with an area of up to 100 square meters. meters. The boiler is designed for parapet installation. And this type of installation makes an exception for this model in terms of the need for forced ventilation. It is not needed here, and combined with the lack of electronics, this gives an advantage in terms of energy independence.
The model is extremely simple to operate - it is mechanical, of course, without any electronic automation in terms of fire control and ignition. But at least there is gas control and protection against overheating of the coolant.
The lack of flexible automatic adjustment is also reflected in a rather mediocre efficiency - 87%. But this is an inevitable compromise for the sake of an affordable price. The heat exchanger is also the most inexpensive - made of stainless steel.
From a review by a Yandex.Market user with the status “Jack of all trades level 2”: “For an apartment, its power is enough, but ten-kilowatt units consume little gas. What I liked - the assembly is good, you can’t tell that it’s from Taganrog. They give a three-year guarantee, I personally have worked for a year so far, and haven’t found anything bad during that time.”
Advantages
- simple and reliable circuit;
- energy independence;
- gas control;
- protection against coolant overheating;
- thermometer;
- three years warranty.
Flaws
- mediocre efficiency;
- minimal functionality.
Bosch Gaz 6000 W WBN 6000-24 N, single-circuit
Rating: 4.7
As number two, let's look at a more expensive, but much more interesting version of the famous Bosch brand. This is two and a half times more powerful 24 kW device with powerful additional functionality.
The main advantages of this model are the presence of an 8-liter expansion tank and a circulation pump with blocking protection. This kit significantly increases the operational safety of both the boiler itself and the entire heating system in the house by maintaining a stable coolant pressure and compensating for its excess due to temperature expansion.
The key element of the design is the burner, which is expensive and of high quality, made of copper. This in itself provides good heat transfer. Energy efficiency is promoted by control automation, flame modulation, and automatic electric ignition. An element of comfortable operation is the automatic diagnostic system. There are also all the necessary protective equipment - gas control, protection against freezing and overheating.
The device can operate on natural and liquefied gas. Weighs only 32 kg and is designed for wall mounting. Despite all the advantages, this particular model receives some criticism from experts for its good, but far from outstanding efficiency in its class - no more than 90%.
From a review by a Yandex.Market user with the status “Jack of all trades level 2”: “Quiet, there have been no breakdowns for several years. With the connected openterm remote control, it warms the heating system very comfortably. The dimensions are not too large, which is good news.”
Advantages
- brand;
- copper heat exchanger;
- circulation pump;
- built-in expansion tank;
- flame modulation;
- protective automation;
- connection of a warm floor;
- 2 years warranty.
Flaws
- mediocre efficiency.
BAXI LUNA-3 1.310 Fi, 31 kW, single-circuit
Rating: 4.7
Again in our review is the British-German brand BAXI, and now it will be a boiler with a closed chamber, and quite high power - 31 kW.
This is already an automatic boiler with a rather rich electronic “body kit” for this price category. There is auto-ignition, flame modulation, and automatic diagnostics. The device supports the connection of external control and can work with a “warm floor” system. There is protection against overheating of the coolant, spontaneous extinguishing of the burner, and protection against freezing.
The great advantages of the model are the presence of a circulation pump and an expansion tank with a volume of 10 liters. And this is all despite the fact that the device itself is designed for wall installation - the dimensions are moderate 450x763x345 mm and the weight is also acceptable - 38 kg.
Electronics require connection to a 220V power supply, preferably through an uninterruptible power supply. This is required not only by the electronics, but also by the built-in exhaust fan.
The boiler can operate on both natural and liquefied gas. Natural is consumed nominally in a volume of 2.59 cubic meters. m/hour, liquefied - 2.2 kg/hour.
The model gives a very good efficiency - 93.1%. This is the merit of the control automation and a generally well-thought-out circuit. Plus the fact that an expensive copper heat exchanger is used here.
Advantages
- protective automation;
- control automation;
- circulation pump;
- copper heat exchanger;
- flame modulation;
- connection of external control;
- expansion tank;
- relatively compact;
- wall installation.
Flaws
- no fundamental disadvantages were identified.
Viessmann Vitodens 100-W B1HC043, 35 kW, single circuit
Rating: 4.8
Now in our review is a premium boiler produced by the famous German company Viessmann Werke GmbH & Co. KG. It is one and a half times more expensive than the previous one, but the price is doubly justified, since this is a new generation condensing boiler with previously unattainable efficiency indicators.
Let's start with the main advantage. Thanks to the above-described scheme for using the energy of condensation of water vapor, this model easily leaves behind even the most energy-efficient classic boilers in terms of efficiency. Therefore, the figure of 108.7% indicated in the characteristics is not a mistake and not such an exaggeration, but only an illustration of the real superiority of this type of boiler.
In addition to this main advantage, the device is notable for its other characteristics. It is multifunctional - there is a built-in expansion tank and circulation pump. Supports connection of external control unit.
There is also all the automation for efficient operation, comfortable control, safe operation - gas control, flame modulation, protection against freezing and overheating, auto-ignition, protection against pump blocking.
This boiler also has a well-designed combustion chamber and ventilation in terms of acoustic comfort. The device operates with minimal noise, smoothly adjusting power in a modulation range of 1:6. This allows you to comfortably use the boiler even in a small apartment. Smooth automatic load adjustment also helps to extend the service life.
At first glance, it may seem that the use of a steel heat exchanger in this model is a disadvantage, since in expensive boilers the best solution is copper or cast iron. But in this case, the manufacturer worked this point well. This is not just steel, but an Inox-Radial surface, which has proven itself in terms of heat transfer, reliability and durability. This is confirmed at least by the fact that Viessmann provides a separate guarantee for the heat exchanger for a period of 10 years.
Advantages
- condenser;
- top efficiency;
- circulation pump;
- expansion tank;
- control and protective automation;
- quiet operation;
- 10 years warranty on heat exchanger.
Flaws
- no obvious deficiencies were identified.
Buderus Logamax plus GB172-42 i, 41.9 kW, single-circuit
Rating: 4.9
The review will be completed by a premium boiler from the Buderus brand, a division of Bosch. This is a powerful and energy-efficient device with top efficiency and wide functionality.
Like the previous model, this boiler uses technology to obtain latent energy from the process of condensation of water vapor. That is, the condensation factor is also added to the combustion energy. This allows you to obtain efficiency that is inaccessible to classical schemes. Here this figure is 109%. Let us emphasize once again that such an “impossible” figure is obtained due to processes not directly related to the energy of gas combustion.
The heat exchanger material is aluminum with all its advantages - compactness, light weight, absolute resistance to corrosion, low thermal inertia.
The device is equipped with all the same automation for control and protection as the above-described model. The flame intensity is smoothly modulated in automatic mode. You can connect external control. There is a self-diagnosis function.
The boiler automatically regulates the heat exchanger pressure using a built-in pump. But it can no longer compensate for temperature changes in volume, since an expansion tank is not provided. But the device, despite all its power, is relatively small (440x840x350 mm) and also weighs moderately - 42 kg, and is designed for wall installation.
In addition, this boiler is also distinguished by its unusually stylish appearance and impressive design. The front panel is made of Titanium Glass. There are black and white options to choose from.
Advantages
- brand;
- condensation;
- top efficiency;
- aluminum heat exchanger;
- automatic control;
- automatic protection;
- circulation pump;
- flame modulation;
- stylish appearance.
Flaws
- no expansion tank.
Selecting the type of boiler
The first question that needs to be resolved is which of the proposed types of boilers is most suitable. Equipment is conventionally divided into two categories:
The most widespread are mounted models, characterized by simple installation, minimal operational requirements and relatively low cost. They are perfect for heating systems of a medium-sized cottage.
If we talk about cost, installation of heating with a wall-mounted boiler costs a modest 700-1000 USD. e. The equipment that is necessary for the operation of the system is provided by the manufacturer in the kit. During the installation process, all that remains is to supply cold water and remove heated water.
Advice. Wall-mounted gas boilers can be installed in any room, for example, in the hallway or corridor. Installation of a floor-standing boiler is recommended in a separate boiler room.
Floor-standing gas boilers are more expensive. Unlike wall-mounted models, they require additional equipment, the purchase of which will increase costs. Thus, installation of floor-standing models costs from 1500 USD. e.
Advice. It is recommended to carry out regular inspections of floor-standing gas boiler equipment every 3-4 years. For mounted models, it is carried out once every 1-2 heating seasons.
When comparing floor-standing and wall-mounted boilers, it is necessary to note the higher level of reliability of models of the first type. The heat exchanger in them is made of cast iron or steel, the heavy weight of which is compensated by resistance to mechanical loads and prolonged exposure to high temperatures.
A little about gas boilers: advantages and disadvantages
The market share of gas heating equipment is about 75%. The rest include solid-state, liquid, electrical or universal analogues. A large category among them are dual-circuit models, presented in a wide variety on the market. Each device is characterized by similarities and differences in design features.
Introductory video lesson
If you choose the right model, taking into account all its main indicators and characteristics, it will provide heat to all rooms in the house. One of the main advantages of double-circuit gas boilers is versatility. Among other positive aspects it is worth noting:
- The ability to automate the boiler relieves the home owner from worries about heating
- Maximum security ensured
- The boiler supplies the house not only with heat in heating radiators, but also with hot water supply (DHW) without installing an additional boiler
- The boilers are compact in size; some models can be hung in a convenient place on the walls, and they do not require a separate boiler room
- Relatively low cost
However, looking at the positive aspects, it is worth highlighting several disadvantages:
- Even having the opportunity to easily organize hot water supply, you will have to wait until heated water flows from the tap
- Normally, a double-circuit boiler is capable of providing hot water to only one point in a certain time period
- The equipment is not able to simultaneously heat the premises and provide a hot water supply line; priority goes to the second operation
- The heat exchangers installed in modern models are very unstable to the effects of hard water: the higher the pH value, the shorter their service life
Selecting the optimal number of circuits
Most models intended for installation in private houses and cottages can be divided into two types according to the number of circuits:
The first ones function extremely simply and are intended exclusively for heating systems. If it is necessary to provide hot water supply in the house, models are purchased that can serve two or more circuits at once.
Advice. When it is necessary to additionally provide hot water to other systems in the house, for example, heated floors, multi-circuit equipment is purchased or modern automation is installed.
Double-circuit gas boilers, which are most widespread, can be divided into two types:
- With built-in boiler
- Flow-through
Boilers with a built-in boiler have one advantage - next to them there is a tank with a capacity of more than 100 liters, in which heated water constantly accumulates. The operation of such equipment allows you to save on fuel, and in the event of a gas shutdown, you can consume the heated liquid for some time. The disadvantages include the need for free space (preferably a separate boiler room) and high starting material costs.
If the need for heated water is small, you can safely use flow-through models. In them, the liquid is heated directly at the moment when it circulates through the circuit.
Do I need a boiler?
The market for single-circuit boilers, in the fight for competition with double-circuit boilers, assumes the constructive possibility of installing an external indirect heating boiler.
The need for its use will depend on the user’s decision and the actual conditions for receiving central DHW services. If an electric boiler is already installed in the house, then naturally there is no need for such a connection.
An indirect heating boiler in single-circuit boilers is an innovative development of modern heating engineers. It has a large water capacity that acts as a storage tank and internal heat exchanger. It is connected to the boiler flow and return parallel to the heating circuit.
The main parameter is power
One of the main characteristics that people pay special attention to when choosing a gas heating boiler is its power. The higher this value in the technical documentation, the larger the area the equipment can heat.
The market is very extensive and offers models whose power ranges from a few units to hundreds of kW.
Advice. In order not to make a mistake when choosing equipment, it is recommended to contact a specialist. A qualified technician will quickly select the power based on specific operating conditions.
If you determine the required boiler power yourself, you must proceed from the ratio: 1 kW for every 10 sq. m. In this case, the room should be well insulated, and the height should be less than 3 m. If there is no possibility or desire to insulate the walls of the house, it is recommended to increase the calculated power indicator by 20-30%.
Another pitfall that you will have to face and take into account is the gas pressure in the pipelines. In the technical documentation, manufacturers indicate power, taking into account its nominal value. In reality, the pressure may be lower, especially in remote areas. Consequently, the useful power will be less.
How to choose a single-circuit gas boiler
First, let's look at the key characteristics of boilers that you should pay attention to when choosing.
Number of circuits
- this is the most obvious parameter that determines the very purpose of the boiler. If the task is to provide both heating of the room and heating of water, a double-circuit boiler is needed. Relatively inexpensive models work alternately - when hot water is turned on, the boiler switches to water heating mode, and heating of the room is temporarily suspended. At the same time, 2-circuit boilers with a built-in boiler operate in two modes, where there is always heated water, but these are mainly expensive models with floor installation.
But if you need a boiler only for heating, a single-circuit one will be enough, and these are the options we will consider. Such models are on average more compact than double-circuit ones, can often be easily placed on the wall, have a generally simpler design, are less demanding, less vulnerable and, all other things being equal, are cheaper than double-circuit ones.
Power
The second key characteristic is power.
. It determines how much area of the room the boiler can handle. The larger the house, the greater the power should be. The approximate ratio is 1 kW per 1 square meter of heated room. But this is only an approximate correlation that allows you to estimate the price. To accurately select a boiler based on power, it is advisable to contact a specialist who will inspect the room, determine its features, take into account insolation and climatic factors, and make recommendations based on the data obtained.
Floor or wall
For wall installation, as a rule, models of low and medium power of no more than 30 kW are suitable. High-power options are often only floor-mounted, especially those with a built-in boiler. Our review will present mainly wall-mounted options with a power of less than 30 kW, but there will also be two examples with a power of over 40 kW, and also wall-mounted.
Burner type
Boilers are also distinguished by the type of combustion chamber
- open or closed. Open ones use room air to burn gas, and combustion products are removed naturally through a chimney and are usually not equipped with an active fan. This gives a plus in terms of price and energy independence - no connection to the power grid is required.
Boilers with a closed burner use air taken from outside, from the street, and the combustion products are removed by a built-in fan. Such boilers do not need a chimney, but they are relatively noisy, depend on electricity and are on average more expensive.
Heat exchanger type
Gas boilers can use different heat exchange schemes. The simplest and most affordable option is with a bithermal heat exchanger. It is used in both single-circuit and double-circuit boilers. To complete the picture, we will inform you about both types, not only for the single-circuit circuit.
In schemes where both circuits are closed to one heat exchanger, there are no complex components, the equipment is less vulnerable and the cost of such models is lower. The downside is that the coolant (water) does not circulate in one of the circuits when the other circuit is running, but it still heats up. This contributes to the overgrowing of the heat exchanger channels with scale, which requires more frequent and responsible maintenance.
There is also an important point related to safety. If for a long time the boiler worked only for heating, and then turn on hot water, then literally boiling water may come from the tap for some time. This is the same heated coolant. You need to remember this when installing a boiler of this type.
A more advanced scheme involves the presence of two heat exchangers - the main and the secondary. The main one is located directly above the burner, and the secondary one is in another part of the boiler. The secondary heat exchanger is heated not by the flame, but by already heated water circulating through a small circuit. This approach increases the durability of the boiler, maintainability and safety of use - the water does not heat up on its own to extreme temperatures.
Heat exchanger material
The heat exchanger in the boiler is the most vulnerable part, since it bears the entire workload - thermal, mechanical and chemical (water composition, scale formation, temperature deformations). It is also the most expensive, since the efficiency of heating and the accuracy of temperature control depend on the efficiency of heat transfer. The materials used here are different, each has advantages and disadvantages:
- Cast iron
. Such heat exchangers are durable - they last for decades without burning out, are not subject to corrosion, and are heat-intensive. But they are heavy and are used only in floor-standing boilers. In addition, they are quite noticeably afraid of sudden temperature changes. - Stainless steel
. These heat exchangers are also quite strong and reliable, but they are still susceptible to corrosion at the welding points. This is the most common type, including for wall-mounted boilers. - Aluminum.
This is a good option for weather-controlled heating, as aluminum has extremely low thermal inertia. This metal is also not afraid of corrosion. - Copper.
Excellent heat transfer, low susceptibility to corrosion, but high price.
Manufacturers often indicate a certain established durability of the heat exchanger, but these data are most often conditional, and in fact this part lasts much longer without any problems. In addition, modern boilers are often equipped with additional add-ons such as weather-dependent units, all kinds of electronics and automation, which in total can significantly offset the disadvantages of one or another type of exchanger.
Condensing boilers
It’s worth saying a few words about a special type of boilers - condensing boilers. This is a relatively new technology; mainly convection-type boilers are on sale.
Condensing boilers are characterized by the highest efficiency due to the extraction of latent energy released during the condensation of water vapor. It makes sense to choose this type of boiler for a home where it is expected that there will be panel radiators or a “warm floor” system. Condensation models are significantly more expensive than convection models, but in the long run they provide significant savings and pay for themselves.
Condensing boilers
A few words should be mentioned about condensing-type boilers, which can be floor-mounted or wall-mounted. Their main difference from classical models is their high efficiency, which exceeds 100%.
The main disadvantage of such equipment is the high initial costs. For their operation, high-power radiators are required. Warm floors work best with them. Heating must be designed in such a way that the coolant flows to the return with a temperature not exceeding 35-40 degrees.
If we talk about the initial costs, they can reach 3-5 thousand dollars. However, the savings are more than significant. It will be possible to heat a house with an area of 150-200 square meters for a modest 40-50 USD.
PS (post scriptum)
Buying a double-circuit electric boiler for heating an apartment in the future does not bring any benefit to its potential owner. If you buy heaters for the heating system and hot water supply separately, it will be much cheaper and more convenient. It’s generally better to forget about water heated floors powered by an electric boiler. There is an alternative - electric heated floors, of which there are several types. The possibility of a coolant leak is eliminated, and even if a breakdown occurs, only some part of the heated floor will cease to function. The newest infrared mats are not susceptible to damage at all.
Gas heating boilers
If the house has a gas supply, installing this type of heating device will be the most ideal option. A gas boiler has two undeniable advantages: low fuel cost and high efficiency (more than 96%).
Modern gas appliances vary in installation option and can be:
The former are distinguished by their compactness, but at the same time low power. These devices are excellent for heating rooms whose total area does not exceed 100 m2. floor-standing boilers have high power (more than 40 kW). Installation of such equipment is carried out on the floor.
In addition, gas boiler models differ in the type of heat exchanger installed. There are single-circuit, double-circuit and triple-circuit gas appliances. Single-circuit ones are designed exclusively for heating the room. In addition to heating, double-circuit boilers are capable of providing the user with hot water and, most importantly, in sufficient quantity. Thanks to the presence of a third circuit, three-circuit gas boilers are capable of heating water, which is intended to be supplied to the heated floor system.
Gas boilers can have a steel, copper or cast iron heat exchanger installed. Each of them has its own advantages and disadvantages, for example, steel is characterized by high strength, but low resistance to corrosion. On the contrary, a cast iron heat exchanger has high anti-corrosion resistance, but is afraid of mechanical damage. The copper heat exchanger is able to please with its resistance to mechanical damage and increased resistance to corrosion. Depending on the type of boiler, a heat exchanger is installed. Thus, cast iron and steel are installed only in floor-standing heating boilers, and copper, due to its low weight, is installed in wall-mounted gas boilers.
Boilers can have a ventilated or atmospheric burner. The latter are in most cases installed in inexpensive boilers with low power. The combustion chambers in such boilers are of closed and open type.
Models that have a closed chamber have a fan in their design, the task of which is to ensure the forced removal of exhaust gases into a coaxial pipe. Devices with an open camera have a slightly simpler version of operation. Exhaust gases are discharged outside through the chimney naturally, and as for the air that is required for the normal operation of the device, it is taken directly from the room in which the gas boiler is installed.
Ventilated burners are highly efficient. In addition, it is important to note that the design of these burners is very complex, and therefore their cost is an order of magnitude higher than atmospheric type burners. The removal of gases in such devices is carried out exclusively in a forced manner. You can also read the article “What is a condensing gas boiler”.
Heating connection diagram
The connection (piping) of the boiler is carried out according to certain rules and standards. It is imperative to comply with all requirements in order to avoid unpleasant consequences. Connection diagrams for single-circuit boilers are no different from double-circuit boilers.
Basic Rules:
- The installation of a single-circuit boiler should take place in a room fenced off from other living rooms.
- The volume of the room where the boiler is located should not be less than 14 cubic meters. There must be sufficient space around the device to allow access for maintenance.
- The heating units must be connected strictly in accordance with the technical documentation. All standards and requirements are usually specified in the operating instructions.
- An external boiler can be connected to the boiler only if this is technically possible. If such an option is not provided initially, connecting any third-party units is a gross violation of the rules.
- The piping scheme must include water treatment and circuit recharge systems. Volatile boiler models are connected via a stabilizer or UPS,
A test run of the unit is carried out in the presence of a competent specialist from the company that sold the boiler. Experts also evaluate the correctness of installation. After which a mark is placed in the documents indicating that the boiler has entered the operating state.
If the task is to use the boiler not only for heating, but also for hot water supply, then it is recommended to connect it to an indirect heating boiler.
The design diagram of a single-circuit gas boiler is standard for many manufacturers and looks like this:
Electric heating boilers
It is immediately worth noting that electric boilers have the greatest number of advantages such as:
– quiet operation;
– ease of operation;
– low cost of equipment.
All existing electric boilers are divided into:
The latter in their design have a heating element, the operating period of which is more than 10 thousand hours, after which this element is very easy to replace with a new one.
Electrode boilers require periodic cleaning of the heating element to remove scale formed during operation. In addition, it is worth noting that these devices are relatively inexpensive, which makes them even more popular among users.
It is impossible to answer the question with confidence which type of electric boiler is better, since each of them has both its own advantages and disadvantages. As for the disadvantages, the most important one is the high cost of the fuel used, that is, electricity, which makes it difficult to use it to heat a large house. Electric boilers are an excellent option as an additional source in case the main one, for example, a gas one, fails for some reason.
Heating of a private house and apartment
Choosing the type of heating for your home, or rather choosing a heating boiler for your home, begins with the fundamental selection of a heating boiler by type, the planned fuel required for the operation of the boiler.
In Russia, in terms of cost, the cheapest fuel is main gas. If you are lucky and in your village it is possible to connect your house to the main gas pipeline, this needs to be done. To connect to the gas pipeline, you need to go through all the stages of the so-called home gasification procedure, from collecting documents to installing a home heating system. You can read about all the stages of this difficult process in the section: Gasification at home.
As you already understand, you will have to select and install a gas boiler at the stage of preparatory work before connecting to the gas pipeline. Unless, of course, you are changing the heating boiler and are already connected to the main gas.
Liquid fuel boilers
These models have many similarities with gas appliances; the only thing that distinguishes the models is the type of fuel used and the type of burner installed. In order to install an oil-fuel boiler, you do not need to obtain a special permit. It is important that this type of boiler is absolutely independent of electricity and gas.
Installation of this type of device requires a special place; in addition, it is necessary to provide a place where the fuel tank will be installed. It should also be noted that during its operation, the boiler smokes very heavily, which is why there is a fairly frequent need to service the device, that is, to clean it from carbon deposits and soot.
